Processes are known for the manufacture of acrylic esters, in particular methyl acrylate and ethyl acrylate, by direct esterification of acrylic acid by the corresponding alcohol, for example catalysed by sulphuric acid. In such processes, large amounts of unreacted alcohol are collected at the outlet of the reactor.
For environmental and economic reasons, it is essential to recover the unreacted alcohol, in order generally to recycle it to the reactor.
To this end, it is known to distil the stream of products or also to scrub it using an aqueous stream.
The documents FR 2 509 294, U.S. Pat. No. 5,435,892 and FR 2 884 514 provide examples of such processes for the production of acrylic esters.
In the document EP 1 721 886, the crude acrylic ester mixture is subjected to different treatments targeted at separating the catalyst and at concentrating and purifying the desired product. These treatments can be carried out by scrubbing, neutralization and/or extraction. The equipment examples cited are mixers/decanters, extraction columns or stirred tanks. The extraction columns are of packed, plate or rotating disk type. The process for the production of methyl acrylate is illustrated using a treatment combining an extraction of the reaction mixture in a packed column with a filtration. However, the residual alcohol content of the extracted organic phase remains of the order of 0.1% to 0.2% by weight.
There still exists a need to succeed in more efficiently recovering the alcohol at the outlet of the reactor.